Paper detail

Reaction pp -> pp πππas a background for hadronic decays of the eta-prime meson

Isospin violating hadronic decays of the ηand η' mesons into 3πmesons are driven by a term in the QCD Lagrangian proportional to the mass difference of the d and u quarks. The source giving large yield of the mesons for such decay studies are pp interactions close to the respective kinematical thresholds. The most important physics background for η,η'\toπππis coming from direct three pion production reactions. In case of the ηmeson the background for the decays is relatively low (approx 10%). The purpose of this article is to provide an estimate of the direct pion production background for the η'\to 3πdecays. Using the inclusive data from COSY-11 experiment we have extracted differential cross section for the pp\to pp-multipion production reactions with the invariant mass of the pions equal to the η' meson mass and estimated an upper limit for the signal to background ratio for studies of the η'\toπ^+π^-π^0 decay.